The present invention relates generally to partitions in structural members and more specifically to self-sealing partitions for use in forming a barrier in a channel.
Channels are often present in structural members such as automotive pillars and the like in which it is desirable to block out fumes, water, dust, and other materials as well as sound traveling along the channel. As will be appreciated by those skilled in the art, water, particularly if it contains road salt, may cause corrosion of metal surfaces. The problem of corrosion is especially acute where there is a gap in the various protective surface coatings that are typically applied to the metal. In addition, pillar channels may serve as pathways for air-borne dust and unwanted sound into the vehicle cavity.
A number of approaches have been taken to provide a suitable barrier for pillars and the like in the automotive industry. One such approach is described in U.S. Pat. No. 4,810,548 entitled, xe2x80x9cSandwich Seal Fixture.xe2x80x9d Therein, a barrier fixture is disclosed having an expandable foam material provided as a core between two registering flanking plates of relatively rigid material. Means are also provided by which the three components (plate-resin-plate) are held together. Mounting brackets are provided on the metal plates to allow the partition to be secured in position in a cavity. The fixture is sized with respect to a passageway to achieve ingress and egress to the passageway. After the fixture is mounted in place in a channel, sufficient heat is supplied to thermally activate a blowing agent in the core. As the core expands (foams) it extends out from the sides of the plates and forms a seal at the channel walls. In this manner a barrier or partition is formed in the channel.
Although the aforementioned fixture adequately forms the desired seal-in-place barrier, it suffers from several drawbacks. Most conventional sandwich fixtures of this type use metal as the plate material which adds additional weight to the fixture. As will be appreciated to those skilled in the art, due to fuel consumption goals, it is important to minimize weight wherever possible in motor vehicle manufacture. In addition to the weight factor, these conventional sandwich fixtures require assembly of three discrete parts. Also, the metal and the resin sheets must be cut to size and then secured together using some type of attachment means. The processing and assembly of the components are excessive.
It would be desirable to provide a self-sealing partition for use in blocking a channel which is light-weight when compared to conventional structures. It would also be desirable to provide a self-sealing partition which is an integral body of materials rather than a plurality of mechanically attached parts.
It is an object of the present invention to provide a lightweight, self-sealing partition for creating a barrier in a channel.
It is a further object of the present invention to provide a self-sealing partition which is a one piece integral body that does not require mechanical interlock of parts.
It is still a further advantage of the present invention to provide a self-sealing partition which does not require the use of metal fasteners and an intervening resin layer.
In one aspect, the present invention provides a cast or molded self-sealing barrier or partition which has a rigid resin-based body portion and an thermally expandable resin-based seal portion. The expandable seal portion includes a region near or at the outer perimeter of the rigid body. A mounting feature is provided on the body portion. The mounting feature is used to secure the barrier in place in a cavity such as the channel of a motor vehicle pillar. Installed in a pillar, the body portion has a configuration which closely matches the channel shape. Upon activation of the blowing agent, the thermally expandable portion expands and seals the gap between the channel walls and the rigid body, thereby sealing the barrier in place.
In another aspect, the thermally expandable portion comprises a plurality of expandable pellets. The pellets may be bonded to the surface of the rigid body through the use of an adhesive or they may be partially embedded in the surface of the body. The pellets may be embedded by placing them in the mold with the resin that forms the rigid body before the resin solidifies.
In still another aspect, the rigid body portion of the barrier is designed to minimize mass. A number of cavities are provided in the rigid body on the surface opposite that on which the expandable pellets are disposed to decrease weight.
In still another aspect the mounting brackets are integrally formed of the same material used to form the rigid body during the casting or molding process.
These and other objects, features and advantages of the invention will be more fully explained in connection with the detailed description of the preferred embodiments and in connection with the drawings.